desktopToDarwinBundle: Include TOC in generated ICNS file

In order to compose a `.icns` file containing multiple icon sizes I had
to pass `--toc` to `icnsutil`. This did not seem to have a negative
effect on `.icns` containing only a single icon size.

pkgs/build-support/setup-hooks/desktop-to-darwin-bundle.sh

@@ -132,8 +132,8 @@ convertIconTheme() {
     }
 
     iconsdir=$(getIcons "$sharePath" "apps/${iconName}" "$theme")
-        icnsutil compose "$out/${iconName}.icns" "$iconsdir/"*
     if [[ -n "$(ls -1 "$iconsdir/"*)" ]]; then
+        icnsutil compose --toc "$out/${iconName}.icns" "$iconsdir/"*
     else
         echo "Warning: no icons were found. Creating an empty icon for ${iconName}.icns."
         touch "$out/${iconName}.icns"